Urea-free Printing Of Cellulose Fabric With Reactive Dyes

Reactive dyes have excellent dyeing properties and fastness,so they are widely used in the dyeing and printing of cellulose fibers.The traditional method of reactive dyes printing process,especially to reactive dyes printing of viscose fabric,due to the high degree of crystallinity of viscose fiber surface with a dense cortex,requires a large amount of urea to dissolute dyes,swell fibers,and promote dyes and fibers fixation.However,urea is easily decomposed into carbon dioxide and nitrogen compounds,which not only increases the chemical oxygen demand,but causes excessive algal blooms and eutrophication of the water,and it becomes a great burden on environmental protection.In recent years,the urea alternatives studied are mostly used in the reactive dye printing process of cotton fabrics,and few of them can be used for viscose fabrics.Considering hygroscopicity,infiltration,providing alkali and protonic for the reactive dyes nucleophilic reaction,Sub.T was used as a substitute for urea to printing cellulose fabrics with reactive dyes.This paper studied the performance of Sub.T and its influence on cellulose fiber,reactive dyes and printing paste.It was found that the Sub.T has good thermal stability and promoted moisture absorption of cellulose fibers,has no negative effects on the absorption spectrum or functional groups of reactive dyes and printing viscosity index（PVI value）.So Sub.T has the potential to replace urea in printing cellulose fabrics with reactive dyes.In this paper,cotton and viscose fabrics were used as printing fabrics.Based on the traditional method of reactive printing process,the reactive red P-BN,reactive yellow P-2RN,reactive blue PGR and reactive blue P-3R were studied.The properties of cellulose fabrics with urea-free printing were characterized by K/S value,color light,permeability,color fastness and fixation rate of reactive dyes.The nitrogen content,ammonia nitrogen content,and CODCr value of the printing waste water were also tested.The results showed that urea-free reactive printing of cotton fabrics can be carried out with 5.0%of Sub.T and the color depth,fixation,color fastness to washing and rubbing are equivalent to those of urea prints.For viscose fabrics,except for some sensitive colors,urea-free printing fabric can achieve the same effect as urea printings.And the urea-free printing conditions were as follows:Sub.T 5.0%,sodium carbonate 3.0%,saturated steaming for 10 minutes.The urea-free printing process can reduce the total nitrogen content of90.5%,the ammonia nitrogen content of 60.0%,and the COD_Cr value of 35.6%.